manchester tank nameplate

[RT-NY]

All manchester RV ASME tanks have a nameplate like the picture attached. I am thinking now that the GAL (gallons) number is probably the total capacity of the tank (30 gallons here) and must be multiplied by .8 to get the actual safe capacity (24 gallons in this case). Is this correct? Or is that number the actual safe capacity itself?

[jojobafanzi]

Originally Posted by RT-NY

All manchester RV ASME tanks have a nameplate like the picture attached. I am thinking now that the GAL (gallons) number is probably the total capacity of the tank (30 gallons here) and must be multiplied by .8 to get the actual safe capacity (24 gallons in this case). Is this correct? Or is that number the actual safe capacity itself?

30 gallons should be water capacity. Actual gas capacity would be 80% of that.

[Ken Allan]

The nameplate lists the tank total interior volume.
30 x .8 = propane capacity.

[RT-NY]

Originally Posted by jojobafanzi

30 gallons should be water capacity. Actual gas capacity would be 80% of that.

OK. But, when people talk about those portable BBQ tanks, they say that they are 20lb tanks, which, in that case, if I understand correctly, is the amount of propane that you should put in the tank not the total tank capacity - the 80% is already taken into account: 20lbs, about 4.7 gallons of propane, Is this correct?

[jojobafanzi]

Originally Posted by RT-NY

OK. But, when people talk about those portable BBQ tanks, they say that they are 20lb tanks, which, in that case, if I understand correctly, is the amount of propane that you should put in the tank not the total tank capacity - the 80% is already taken into account: 20lbs, about 4.7 gallons of propane, Is this correct?

No. The weight is calculated by the water capacity of the tank but using the weight of propane. Once you have that figure, take 80% of that and you have your propane fuel capacity. Newer tanks hold around 3.4 gallons of propane and older tanks up to 3.8 gallons. The larger companies like Blue Rhino are shorting the customers to keep the profit up on the exchange programs. Capitalism. LOL!

[Ken Allan]

The DOT (so called) 20# tanks are different. They are made to be portable and I think the 20# is just an approximation of what you will be lifting. Example: My BBQ frill tank weighs 22-23# when full. That is the weight of the tank AND fuel.

Our ASME tanks are rated differently as they are intended to be "bolted" in place like on our vans or RV. That is not considered portable.

ps... I find the term "water capacity" confusing. What we are talking about is the interior volume. Same thing though.

[jojobafanzi]

Originally Posted by Ken Allan

The DOT

ps... I find the term "water capacity" confusing. What we are talking about is the interior volume. Same thing though.

I didn't design the terms used in the propane industry. Water capacity on a propane tank is a term thrown around every day at propane gas companies. For example. A service tech will go to a job with a work order to replace two 420's. Referring to replacing two 420 pound tanks. In reality, the tanks can hold 100 gallons of water or 100 gallons of propane if filled to the very top which is never done. The term 420 refers to the theoretical capacity of propane of 100 gallons and multiplied by the weight of propane at 4.24 lps per gallon. Motor vehicle mounted tanks is something I am not an expert on but the concept has to be the same. Leave at least 20% room so the fuel can vaporize. Gauges and overfill protection devices can malfunction. The specifications are stamped into the tanks.